1. Field of the Invention
This invention relates to a one-way clutch and to winding and rewinding devices for cameras using the same.
2. Description of the Prior Art
The one-way clutches which have been widely used in the past are known as providing transmission of rotation in a given direction of an input shaft to an output shaft. In the operation of such clutches, when relative motion of the input shaft and the output shaft is in a certain given direction, the input shaft and the output shaft are interlocked to enable transmission of rotation therebetween. Therefore, the relationship between the output shaft and the input shaft is such that there exists a dependence on each other whereby a problem may arise in that the output shaft cannot be left completely free from the input shaft. That is, in the conventional one-way clutch, when applied to a system where some rotative force is imparted to the output shaft other than through the input shaft, there arises the possibility that rotation will be reversely transmitted from the output shaft side to the input shaft side. If such system is, for example, employed to wind and rewind film in a camera, the reliability of its operation will be seriously damaged.
In the prior art, it is known to provide an apparatus using a pair of such one-way clutches arranged between the motor and a winding system and between the motor and a rewinding system so as to produce opposite directions of transmission so that the driving torque of the motor is selectively transmitted to the winding and rewinding systems depending upon the direction of rotation of the motor as disclosed in Japanese Patent No. Sho 43-4138 (published Feb. 15, 1968). However, in the winding and rewinding device of the camera, as described above, when film winding or rewinding is being performed, the driving connection of the motor to the takeup side results in that the supply side is also rotated by the motion of the film although the driving torque of the motor is not transmitted thereto. Thus, the diameter of the convoluted film on the takeup side increases, while the diameter of convoluted film on the supply side decreases so that the rotation of the supply side speeds up as the winding of the film goes on. For this reason, in the case of the apparatus of the abovecited Japanese Patent No. Sho 43-4138 constructed by using the one-way clutch which assumes the non-transmitting position due to the relative rotation direction of the input side to the output side, it follows that, for example when rewinding, because the output side of the one-way clutch arranged in the winding up system is rotated by the moving film in a direction to connect the clutch, and for the rewinding goes so far ahead that the speed of rotation of the output side is faster than that of rotation of the input side which is rotating in a direction to cut off the clutch by the reversed rotation of the motor, the following problem will arise. That is, since, at this time, the one-way clutch which is caused to connect becomes transmitting, the driving torque of the motor is transmitted also to the winding system directly from the motor, whereby the rotation of the winding system is interfered with to render further rewinding impossible.
That is, such a one-way clutch produces a disadvantage in that though, as has been mentioned above, its input side rotates in the direction to render the clutch non-transmitting it is when the output side is rotated in the same direction at a faster speed than that speed by some external force that the connection takes place and that the transmitting state operates. Therefore, the winding and rewinding device for a camera using this one-way clutch can not avoid the above-described drawback. On this account, in the art of winding and rewinding devices for cameras using the conventional type of one-way clutch, to provide assurance that the winding and rewinding proceeds without interference, it is required to employ a changeover means for connecting and disconnecting the driving torque transmitting gear. This requires an objectionably large increase in the complexity of the structure and the bulk and size. Also, there is an additional drawback in that it is difficult to build it into a small-sized camera.